If you fail to complete this quest within the 10 minute limit of the disguise, just return to Adriana and she will disguise you again.
If you are a Gatherer DO NOT finish this quest until you are just sick of harvesting here. This 10 minute disguise will let you roam all over the Redoubt safely, and harvesting does NOT break the disguise! Just be sure you are back in Adriana's cell before the 10 minutes expires...